MM-34871 CRT: Participants of thread include non-replying followers (and past followers) (#17447)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/store.go

@@ -289,7 +289,7 @@ type ThreadStore interface {
 	GetMembershipsForUser(userId, teamID string) ([]*model.ThreadMembership, error)
 	GetMembershipForUser(userId, postID string) (*model.ThreadMembership, error)
 	DeleteMembershipForUser(userId, postID string) error
-	MaintainMembership(userID, postID string, following, incrementMentions, updateFollowing, updateViewedTimestamp bool) (*model.ThreadMembership, error)
+	MaintainMembership(userID, postID string, following, incrementMentions, updateFollowing, updateViewedTimestamp, updateParticipants bool) (*model.ThreadMembership, error)
 	CollectThreadsWithNewerReplies(userId string, channelIds []string, timestamp int64) ([]string, error)
 	UpdateUnreadsByChannel(userId string, changedThreads []string, timestamp int64, updateViewedTimestamp bool) error
 }